A regular two-dimensional arrangement of squares separated by vertical and horizontal "canals." Looking at the grid produces the illusion of gray spots in the white area between square vertices. The illusion was noted by Hermann (1870) while reading a book on sound by Tyndall (1869).
Hermann Grid Illusion
See also
Hermann-Hering Illusion, Illusion, Scintillating Grid IllusionExplore with Wolfram|Alpha
References
Fineman, M. The Nature of Visual Illusion. New York: Dover, pp. 139-140, 1996.Hermann, L. "Eine Erscheinung simultanen Contrastes." Pflügers Archiv für die gesamte Physiologie 3, 13-15, 1870.Lingelbach, B. and Ehrenstein, W. H. Jr. "Das Hermann-Gitter und die Folgen." http://www.leinroden.de/304herfold.htm.Lloyd, S. J.-A. "The Hermann Grid." http://web.mit.edu/sjlloyd/www/Perception/.Spillmann, L. "The Hermann Grid Illusion: a Tool for Studying Human Perceptive Field Organization." Perception 23, 691-708, 1994.Tyndall, J. Der Schall. Braunschweig, Germany: Vieweg, 1869.Referenced on Wolfram|Alpha
Hermann Grid IllusionCite this as:
Weisstein, Eric W. "Hermann Grid Illusion." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/HermannGridIllusion.html